Production of metallic designs on nonmetallic materials



- Feb. 10, 1948. F. E. KERFQIDGE} I ,435,

PRODUCTION OF METALLIC DESIGNS 0N NONMETALLIC MATERIALS Filed June 1,1944 FIGJ.

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. INVENTOR FHA WK ENOCH KERRIDG'E I). In: fiffornvy:

Patented Feb. 10, 1948 PRODUCTION OF METALLIC DESIGNS ON NONMETALLICMATERIALS Frank Enoch Kerridge, London,

or to Johnson, Matthey 8: Company England, assign- Limited,

London, England, a British company Application June 1, 1944, Serial No.538,231 in Great Britain June 2,1943

6 Claims.

This invention relates to the production of designs in gold, silver orpalladium on non-metallic application and may be used also for theproduction of decorative or other types of designs in metal on glass andnon-porous ceramic or natural products.

According to this invention I produce a metallic design on anon-metallic material (which I will hereinafter call the base) by aprocess comprising the following steps, namely: a

(a) Providing the base with a thin coating of silver. gold or palladiumevenly distributed over its surface,

lb) Coating the resulting metal surface with a film of light-sensitisedglue or gelatin which is then processed by photographic methods so as totake the form of a positive image of the desired design, i

(c) Hardening the produce a resist,

(d) Removing the metal not covered by the resist by etching with asolution of bromine or iodine in a liquid alcohol or ester which is notreadily attacked by these halogens, thus leaving the designin metalbelow the resist, and (e) firing the article at such a temperature,generally from 500 to 900 C., that the resist is burned away and themetallic design is caused to adhere firmly to the base.

If desired, the opacity and/or resistance to wear of the metallic designmay be improved by:

(f) Applying an electroplated coating of the same or another metal.Since the additional metal is applied by electrodeposition, it isdeposited only on the metallic design, the non-metallic surfaceremaining unaffected,

The thin coating of precious metal in step (a) may be produced by theknown methods of sputtcring or evaporation in a high vacuum. It may alsobe produced by the use of the materials known commercially as "liquidgold. liquid silver" and liquid palladium, which consist mainly ofsolutions of sulphoresinates or resinates of the metals in solvents,such as essential oils. When using liquid metals, a suitable image inknown manner to heating adhere strongly amount of the liquid'is appliedto the surface of the base and the latter is spun by rotating it etc.high speed about a central axis in a horizontal plane so as to causetheliquid to spread evenly over the surface of the base and throw of!any excess of liquid. The base is then fired at a temperaturesufliciently high to decompose the organic constituents of the "liquidmetal but not high enough to cause the resulting metal him to to thebase. A suitable temperature may be between 300 and 600 C.

Commercial liquid metals" contain a considerable quantity of solvents oflow boiling point, such as chloroform, or ethyl acetate, and thepresence of these may cause deposition of moisture during the spinningoperation due to the chilling caused by their rapid evaporation. It istherefore preferred to use in place of these solvents liquids such ascyclohexanol and benzyl alcohol which have a low rate of evaporation.

The glue or gelatin used in step (b) is preferably one of the gluepreparations sold commercially for photo-engraving processes and isrendered light-sensitive by the addition of a soluble chromate orbichromate. A wetting agent may be added to assist in even distributionof the glue over the metal.

A suitable sensitisedglue solution may be composed as follows:

Ammonium bichromate grams 28 0.880 ammonia cc '6 Distilled water cc 660v Wetting agent grams 8 Photoengraving glue cc. 200

image of the design. The parts of the glue film which have remainedsoluble are then removed by washing in cold water and the whole is driedrapidly, whereby the desired design is left as a glue image on thesurface of the metal coating;

This image is then converted into a resist (step (0)) for example byheating for 20 minutes at from 250 to 300 C. Alternatively, thehardening may be effected by treatment with chemical reagents, such asformaldehyde or chrome alum.

The removal of the metal not protected by the resist (step (d)) iseffected by an etching process. The reagent used in this process must besuch that it does'not attack the resist or the underlying metal. Theusual etching reagents for silver, gold and palladium consist of aqueoussolutions of relatively strong acids with or without the addition ofoxidising agents, or of alkaline solutions containing cyanides with orwithout oxidising agents such as hydrogen peroxide or ammoniumpersulphate. All these attack glut resists very readily so that it isdifilcult to remove the metal from the parts not covered by the resistwithout at the same time causing the resist, at least in part, to liftaway from the base and thus expose part of the metallic design to theaction of the etching reagent.

I have found that this difficulty can be overcome by using a etchingreagents solutions of bromine or iodine in non-aqueous solvents which donot penetrate the resist and which are not themselves readily attackedby bromine or iodine. Such solvents are, for example, the loweraliphatic alcohols, such as methyl, ethyl, isopropyl, butyl and amylalcohols polyhydric alcohols, such as ethylene glycol, diethylene glycoland glycerol,

or their esters, preferably their high boiling esters, such as ethyllactate, butyl lactate, amyl lactate and the glycol and glycerolacetates.

As examples of suitable etching baths I may mention:

(1) 2 parts of iodine, 4 parts of potassium iodide and 100 parts ofethyl alcohol;

(2) 100 parts of ethylene glycolmonoacetate, parts of acetic acid and 2parts of bromine; or

(3) 100 parts of ethyl lactate, 10 parts of lactic acid and 2 parts ofbromine all parts being by weight.

Solutions containing bromine act more rapidly than those containingiodine,

The action 01 the etching reagent may be accelerated-by suspendingtherein a solid, as, for example, fine sawdust or levigated alumina,which exerts a mild scouring action on the metal coating when theetching bath is gently agitated,

If the metal coating in step (a) is produced by the use of a liquidmetal," the adherence of the metal coating to the base is efiected byincluding bismuth or other metal resinate in the liquid metal. In thiscase, when the metal is removed by etching in step (d), a thin film ofbismuth, or other metal, oxide may remain adhering to the base. This maybe removed by immersing the base in a dilute acid solution which doesnot attack the resist and in which the metal oxide is soluble, as forexample tartaric acid or citric acid, preferably dissolved in anon-aqueous solvent, for the reasons given above. In some cases thisacid may be added to the etching reagent, so that the metal and themetal oxide are removed at the same time.

The metal applied to the design in step (I) may be the same metal as thedesign, or a different metal. For example by electroplating a layer oirhodium or platinum on to a design in gold, silver or palladium, thedesign is rendered more resistant to wear, denser, and more opaque.

The metals may be applied from appropriate known plating baths, and Iwill describe the applicatlon of rhodium to a gold design on a glasssurface. Other metals may be deposited in a similar manner.

The glass, with the gold design thereon, is first I cleaned by immersingit for a few seconds in a hot solution of caustic soda and sodiumphosphate. The design is then electroplated witt rhodium in a platingbath containing, for example, rhodium sulphate, alkali or ammoniumsulphate and sulphuric acid at a temperature oi 30 C. at a voltage of 12and a current density of from 0.1 to 0.8 ampere per square centimetrefor from 10 to 60 seconds. In this way the design becomes thickerwithout the lines becoming appreciably wider. Since rhodium is a hardermetal than gold, the design is more resistant to wear; it is also moreopaq e.

. The way in which designs according to this invention may be built upis illustrated diagrammatically in the accompanying drawing in which thedimensions of the various layers are greatly exaggerated.

Figure 1 shows the shape of the desired design and Figures 2-8 aresections showing how the design is built up.

Figure 2 shows the base i on which it is desired to produce the design.

Figure 3 shows the base i with a coating 2 oi metal produced by step (a)as hereinbefore described. Y

Figure 4 shows the film of glue or gelatin 3 applied to the metalcoating 2, while Figure 5 shows the film 3 in the form of the designafter exposure to light and removal of the unaffected glue or gelatin.

Figure 6 shows the article after etching by step (d), the metal notcovered by the film 3 having been removed leaving the metal design 2covered by the film design 3.

Figure 7 shows the metal design 2 on the base i after firing by step (e)the film 3 having been burned away.

Figure 8 shows the result of optional step (I) in which the design 2 ismade thicker by electrodeposition thereon of the same or another metal 4which also takes the form of the design.

Iclaim:

1. A process of producing metallic designs on non-metallic materialscomprising the steps: (a) providing a non-metallic material with a thincoating of a precious metal selected from the group consisting ofsilver, gold and palladium evenly distributed over its surface, (12)coating the resulting metal surface with a film of lightsensitisedcolloid selected from the group consisting of glue and gelatin andprocessing said film by photographic methods to produce a positive imagein said colloid of the desired design, (0) hardening said image toconvert it into a resist, (it) removing the metal not covered by saidresist by etching with a solution of a halogen selected from the groupconsisting of bromine and iodine in a solvent selected from the groupconsisting of the lower aliphatic alcohols and the esters thereof, thusleaving the design in metal below the resist, and (e) firing the articleto burn away the resist and cause the metallic design to adhere firmlyto the non-metallic material.

2. A process of producing metallic designs on non-metallic materialscomprising the steps: (a) providing a non-metallic material with a thincoating of aprecious metal selected from the group consisting of silver,gold and palladium evenly distributed over its surface by spinning afilm of a composition selected from the group consisting of theresinates and suiphoresinates of the precious metals dissolved in asolvent therefor, onto the surface of the non-metallic articleandthereafter firing to convert said film into a thin coating of thedesired metal, (b) coating the resulting metal surface with a film oflight-sensitised colloid selected from the group consisting of glue andgelatin and processing said film by photographic methods to produce apositive image in said colloid of the desired design,

and iodine in a solvent selected from the group 10 consisting of thelower aliphatic alcohols and the esters thereof, thus leaving the designin metal below the resist, and (e) firing the article to burn away theresist and cause the metallic design to adhere firmly to thenon-metallic material.

3. A process as claimed in claim 2 in which the composition comprises asolute selected from the group consisting of resinates andsulphoresinates of a metal chosen from the group consisting of silver,gold and palladium in essential oils diluted with a solvent having a lowrate of evaporation.

4. A process as claimed in claim 1 in which the solvent for the halogenin step (d) is selected 2 from the group consisting of lower aliphaticmonohydroxylic and polyhydroxylic alcohol and esters of the same.

5. A process as claimed in claim 1 in which the etching bath used instep (d) is acidified with a weak organic acid.

6. A process as claimed in claim 1 in which the etching bath contains asuspended solid.

FRANK ENOGH KERRIDGE.

REFERENCES CITED The following references are of record in th iile ofthis patent:

UNITED STATES PATENTS Number Name Date 321,244 Philippi June- 30, 1885468,591 Baynes Feb. 9, 1892 1,205,723 Friedrich Nov. 21, 1916 1,525,107Spencer Feb. 3, 1925 1,776,535 Bekk Sept. 23, 1930 1,821,561 McFarlandSept. 1, 1931 1,942,686 Colbertet a1. Jan. 9, 1934 2,230,156 Carman Jan.28, 1941 2,375,355 Fahraeus May 8, 1945 OTHER REFERENCES Mellor,Treatise on Inorganic and Theoretical Chemistry, published by Longmans,Green 8: Co., New York, vol. 3 (1923), pp. 346 and 527, and v01. 15(1936), p. 627. r

